Tumors of the alimentary canal, especially, colorectal cancer (CRC) is the third most common malignancy and the fourth most frequent cause of cancer deaths worldwide. The 5-year overall survival rate for all stages is 40-60%, because early diagnosis is difficult and more than half of the patients with CRC ultimately develop locoregional recurrence and/or distant metastases. Furthermore current chemotherapy is tissue non-specific and usually produces severe systemic toxicities. Therefore, it is essential to improve methods for early diagnosis and further to identify novel therapeutic strategies selectively targeting cancer tissues of the alimentary canal.
It is well-known that tumors cannot grow without a blood supply. To this end, growth of new blood vessels from existing ones, i.e. angiogenesis is necessary for tumor growth. Ample evidence has shown that tumor vasculature expresses unique markers that distinguish it from normal vasculature both structurally and physiologically. Vascular cells are genetically stable. Thus anti-angiogenesis therapies provide a promising approach for treatment of tumors of the alimentary canal with higher efficacy and lower toxicity than existing therapies.
The current invention arose from in vivo biopanning with a phage library. In vivo phage display technology has been successfully used as a tool to identify peptides that selectively home to tumor vasculatures. Homing peptides selected by this method have been used as carriers of drugs and imaging agents for cancers.